leucine (Leu L)

Term: leucine

Literally meaning: “pertaining to white”

Origin: Anc Greek

λευκός/leukos(=white)

Coined/History 

Leucine was isolated in 1818 by French chemist Joseph Louis Proust (1754-1855)  from cheese in a white crystalline state. Finally it was named by Fench chemist Henri Braconnot (1780-1855) who isolated it in a pure form from muscle.

Definition

Leucine is an essential amino acid that helps to protein synthesis. It is utilized also  in the liver and adipose tissue. In muscle and in adipose tissue leucine is used in the formation of sterols. It is found in  foods that are high in proteins like eggs, meat, poultry and legumes. 

isoleucine (Ile I)

Term: isoleucine

Literally meaning: “isomer of leucine”

Origin: Anc Greek

ίσος/isos(=equal) combining form ισο-/iso- eg isomer, isopod

+λευκός/leukos(=white)

Coined/History

The term was coined in 1904 by German F Ehrlich who observed that in sugar there was an amino acid very similar but not identical with leucine.  Isoleucine’s constitution established 3 years later with  consequent synthesis via the Strecker reaction.  

Source: Ehrlich,  F.,  Ber.  them.  Ges.,  37,  1809  (1904)   

Definition

Isoleucine is an essential amino acid that with valine and leucine is part of the three “branched chain amino acids” .  Isoleucine helps to muscle recovery blood-clot formation and the regulation of blood sugar levels. Nutritional sources includes eggs, soy protein turkey, chicken cheese and fish